The International Accounting Standards Board will not immediately fall into line behind its US counterpart over proposed changes to impairment in accounting standards. Instead, the IASB will take up the issue as part of its comprehensive review of IAS 39, Financial Instruments: Recognition and Measurement, due to be completed within six months. The move follows intense speculation that the IASB would be forced to follow the proposals issued by the US Financial Accounting Standards Board earlier this month. At the time, the IASB called for views on the FASB proposals which affect 'mark-to-market' accounting rules. Sir David Tweedie, IASB chairman, said: 'We have heard a clear and consistent message on financial instruments accounting - fix this once, fix it comprehensively, and fix it in an urgent and responsible manner.' The IASB also said that another FASB proposal on fair value measurement was consistent with existing guidance on IFRS, creating a level playing field. But to ensure ongoing consistency between IFRS and US GAAP, the IASB said it would include relevant guidance in its exposure draft on fair value measurement to be published in May. The IASB has set out a six-month timetable for the proposal to replace IAS 39. When the IASB called for views on the FASB's proposals, many commentators, including the ICAEW and ICAS, urged the international standard setter not to cave in to pressure to follow the FASB line.